Physics

Electromagnetic Waves and Spectrum

670 Questions

Electromagnetic waves and spectrum questions test a candidate's understanding of radiation frequencies, wavelengths, and the properties of different rays like infrared, ultraviolet, and visible light. Concepts also cover practical applications in astronomy and the fundamental speed of light calculations. This physics topic appears regularly in general science sections of major competitive examinations.

UV rays propertiesElectromagnetic radiation frequencyWavelength identificationSpeed of light calculationsBlack body radiation

Electromagnetic Waves and Spectrum Questions

Multiple choice

Gamma rays measures about one billionth of a meter.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Gamma rays have wavelengths much shorter than one billionth of a meter (typically less than 10 picometers or 10^-11 meters). One billionth of a meter is a nanometer, which corresponds to light in the visible/UV range.

Multiple choice

Gamma radiation transformed Bruce Banner into the Hulk. Which of these is false about gamma rays on the EM spectrum?

  1. They have the shortest wavelength

  2. They have the most energy

  3. They have the longest wavelength

  4. They cannot be seen by humans
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Gamma rays have the shortest wavelengths and the highest energy on the electromagnetic spectrum. Therefore, the statement that they have the longest wavelength is false.

Multiple choice

What part of the electromagnetic spectrum can be directly observed by humans?

  1. Visible light

  2. Ultraviolet light

  3. Radio waves

  4. Gamma rays
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Human eyes contain specialized photoreceptor cells (rods and cones) that are sensitive only to a narrow band of electromagnetic radiation. This specific range is known as visible light, whereas other wavelengths like ultraviolet, radio waves, and gamma rays cannot be detected directly by human vision.

Multiple choice

The electromagnetic spectrum shows a family of EM waves arranged _______.

  1. in alphabetical order

  2. in order of frequency and wavelength

  3. in order of use and application

  4. in order of luminosity and radiation emitted
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The electromagnetic spectrum is organized by the physical properties of the waves, specifically their frequency and wavelength, rather than their utility or luminosity.

Multiple choice

It remains the same for all EM waves.

  1. Energy

  2. Speed

  3. Frequency

  4. Wavelength
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In a vacuum, all electromagnetic waves travel at the same constant speed, known as the speed of light (c).

Multiple choice

EM wave that have the highest frequency.

  1. Infrared rays

  2. Radio waves

  3. Gamma rays

  4. UV rays
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Gamma rays are at the end of the electromagnetic spectrum with the shortest wavelengths and, consequently, the highest frequencies and energy levels.

Multiple choice

EM wave that have the highest wavelenght.

  1. Infrared rays

  2. Radio waves

  3. Gamma rays

  4. UV rays
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Radio waves have the longest wavelengths in the electromagnetic spectrum, which corresponds to their very low frequency.

Multiple choice

Tesla, a high frequency current, is known as the:

  1. red ray

  2. violet-ray

  3. infrared ray

  4. ultraviolet ray
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Tesla high-frequency current is historically referred to as the violet ray due to the color of the gas discharge in the glass electrode. It is not an infrared or ultraviolet ray.